This application is based upon, and claims the benefit of priority of, prior Japanese Patent Application No. 2001-198528 filed on Jun. 29, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fuel supply apparatus in which a supporting member attached to a fuel tank and a sub tank for housing a fuel pump are coupled to each other by a column support.
2. Description of Related Art
Generally, an example of what is commonly referred to as an in-tank type fuel supply apparatus which is designed to house a fuel pump in a fuel tank consists of a flange member of a fuel supply apparatus, attached to an upper wall of a fuel tank, coupled by a column support made of metal to a pump case for housing a fuel pump. In such a fuel supply apparatus, it is preferable that a part of the flange member that extends toward the pump case be made as small as possible in length. This is especially advantageous in a fuel supply apparatus in which an interval between the flange member and the pump case is reduced in keeping with the use of a lower-profile fuel tank.
Moreover, it is preferable to bring the pump case into contact with the bottom of the fuel tank. By doing so, when the fuel remaining in the fuel tank decreases in volume, the fuel contained in the fuel tank is drawn by the fuel pump through a fuel inlet of the pump case. Also, in a case where a sub tank is used as a pump case, and the fuel within the fuel tank is supplied to the sub tank by a jet pump or the like so the liquid level of the fuel within the sub tank raises to a position above the liquid level of the fuel within the fuel tank, the sub tank should preferably be pressed against the bottom of the fuel tank.
To achieve this, in general, the pump case is coupled to a column support in such a way as to be movable with respect to the supporting member, and a coil spring is disposed around the column support. By increasing an urging force exerted by the coil spring, the pump case presses against the bottom of the fuel tank. In a case where the fuel tank is made of resin, the fuel tank may expand or contract due to a change in its internal pressure. This results in deformation of the fuel tank. Therefore, it is necessary to ensure that the sub tank keeps up with deformation of the fuel tank by pressing the pump case against the bottom of the fuel tank using the urging force of the coil spring. In order to secure the urging force of the coil spring required to press the pump case against the fuel tank bottom, and an adequate amount of movement of the pump case relative to the metal column support while being urged by the coil spring, an interval between a tubular portion of the flange member, into which the metal column support is inserted, and the pump case needs to be kept at least at a predetermined length. To secure as long an interval as possible between the tubular portion of the flange member for receiving the metal column support and the pump case, it is preferable that a part of the tubular portion formed in the flange member that extends out toward the pump case be made smaller in length.
In light of the foregoing, a fuel supply apparatus is shown in FIG. 6 in which an insertion portion 102 in the form of a bottomed sleeve, composed of a tubular portion 103 and a bottom portion 104, is formed so as to extend from a plate-shaped flange body 101 of a flange member 100 toward the side opposite to a pump case (not shown), and a metal column support 110 is inserted into the insertion portion 102. A coil spring 111 loads the pump case with a force that tends to move the pump case in a direction away from the flange member 100.
Here, assume that a vehicle experiences a collision and a harsh impact force is applied to the fuel tank mounted therein. In this case, the flange member 100, being attached to the upper wall of the fuel tank, concurrently moves with the fuel tank. The pump case, being coupled to the flange member 100 by the metal column support 110 and being pressed against the bottom of the fuel tank by the urging force of the coil spring 111, is forced to move by inertia even after the movements of the fuel tank and the flange member 100 are stopped. Since one end of the metal column support 110 coupled to the pump case is moved concurrently with the pump case, its other end is forced to tilt obliquely with respect to the flange member 100. That is, the metal column support may not be at a 90 degree angle with the flange member 100. Consequently, a crack 120 may develop in a corner portion which the flange body 101 forms with the tubular portion 103, which results in fuel leaking from within the fuel tank through the crack 120.
In view of the foregoing, an object of the present invention is to provide a fuel supply apparatus which is designed so that, even if a column support receiving portion of a supporting member is broken, the breakage is prevented from reaching both surfaces of the supporting member.
In a fuel supply apparatus according to a first aspect of the present invention, a bottom portion of an outer sleeve, formed continuously with a bottom portion of an inner sleeve for receiving a column support, is located on a same plane as the bottom portion of the inner sleeve, or extends farther on an opposite side of a pump case than the bottom portion of the inner sleeve. By this construction, even if a harsh impact force is applied to the fuel supply apparatus and as a result cracking occurs in a corner portion which a tubular portion of the inner sleeve forms with the bottom portion thereof, the resultant crack is prevented from reaching the tubular or bottom portion of the outer sleeve. That is, both surfaces of a supporting member are free from cracking. Accordingly, even if a crack develops in a column support receiving portion of a supporting member in a state where the fuel supply apparatus is attached to the fuel tank, fuel within the fuel tank is prevented from leaking through the crack to the outside.
Further, since the inner sleeve extends farther on the opposite side of the pump case than a supporting body, the length of the part of the inner sleeve that protrudes toward the pump case decreases. In the foregoing description, the pump case may be coupled to the column support so as to be movable along a longitudinal direction of the column support. The coil spring may load the pump case with a force that tends to move it in a direction away from the supporting member. Accordingly, it is possible to ensure that the pump case remains pressed against the bottom of the fuel tank in a state where the fuel supply apparatus is attached to the fuel tank.
Additionally, the sub tank to which the fuel within the fuel tank is supplied may be used as a pump case for housing a fuel pump. By keeping the level of the fuel within the sub tank higher than the level of the fuel within the fuel tank, even if the fuel remaining in the fuel tank becomes lower in volume, the fuel pump will be able to reliably draw in and discharge the fuel within the sub tank.
Furthermore, the inner sleeve may have a rib formed at the outer periphery thereof. This helps improve the strength of the inner sleeve, and consequently the inner sleeve becomes resistant to breakage. When an impact force is applied to the fuel supply apparatus, breakage tends to occur particularly in the mechanically weak portion formed in the inner sleeve""s tubular portion for receiving the column support. Consequently, in the foregoing construction, the inner sleeve may have a mechanically weak portion formed in the tubular portion, thereby the parts of the inner sleeve other than the tubular portion are protected from cracking. Furthermore, the supporting member may be made of resin and thus can be molded in one piece with ease.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.